Organic Garden Pest Control & Prevention

Organic garden pest control aims for a balanced garden ecosystem that naturally keeps harmful pests away while facilitating rigorous, unimpeded plant growth and long-term soil health…

• Types of Pests
• Prevention: Level 1 - Healthy Plants (Harmful Insects & Disease)
• Prevention: Level 2 – The Pest-Reducing Garden Layout (Harmful Insects & Disease)
• Prevention: Level 3 – Encouraging Predators of Harmful Insects
• Control: Level 1 – Gardener Intervention (Harmful Insects, Disease, Mammals)
• Control: Level 2 - Natural Pesticides, Biological Controls & Other Options (Harmful Insects & Disease)

Types of Pests Targeted By Organic Garden Pest Control

Pests come in all shapes and sizes, from tiny insects to large mammals. Here’s what you’re up against…

• Disease - Microscopic pets called pathogens (bacteria, fungi, pathogenic nematodes and viruses) cause disease, which shouldn’t be much of an issue after starting a garden that is naturally healthy. But if you’re still working to get your soil to where it needs to be, they could present a problem.
  
  See our Common Plant Diseases page (coming soon) to learn how to identify and control garden plant disease.
• Garden slugs and snails – Slugs and snails enjoy munching on just about everything in your garden. They tend to come out at night, and since they move at a snail’s pace you can catch them in the act if you run out at night with a flashlight.
  
  If you want to avoid looking like a garden burglar, then keep your eyes peeled for a couple of telltale signs, including chewed holes in your plants’ leaves along with, to add insult to injury, a trail of slime.
• Harmful insects (don’t confuse with the beneficial insects discussed below) – Insects in your garden can be harmful in adult form, larva form or both. To see photos of the most common types along with descriptions and damage caused, check out this resource.
• Mammals – Mammals are especially frustrating given the large amount of damage they can do in such a short amount of time. Some are craftier than others (burrow, jump, climb, catapult… you name it), so we’ll address how to outsmart the brightest of the vandals further down the page. Here are some of the more common mammalian garden adversaries:

Armadillos Cats Chipmunks Deer Dogs Gophers Hares

Mice Moles Prairie dogs Rabbits Raccoons Skunks

Squirrels Woodchucks Wild turkeys Voles The Ever-Feared Garden-Shear-Wielding Aunt Bessie

Prevention: Level 1 - Healthy Plants for Organic Garden Pest Control (Harmful Insects & Disease)

Now that you have some idea of what you’re up against, let’s discuss the foundation of a pest-controlled organic garden. Notice we said pest-controlled, not pest-free. After all, pests exist in nature and most wild plants seem to get along just fine. Your garden goal is to tip the scales in your favor to keep their presence at a minimum.

Towards this end, first consider what pests like…

Mammals like you, me, deer, raccoons and The Ever-Feared Garden-Shear-Wielding Aunt Bessie like our veggies fresh and healthy. But harmful insects and disease have an altogether different appetite that you can use in your favor: they prefer weak, unhealthy plants.

To keep harmful insects and disease at bay, your objective should be to keep your plants and soil as healthy as possible by…

• Choosing the right garden spot for proper sun, wind, moisture and temperature
• Nurturing healthy soil through composting and proper garden soil pH
• Staying out of the garden when your plants are wet to avoid spreading disease
• Watering plants in the morning to give them a chance to dry before sundown (thus discouraging the wet- and darkness-loving disease-causing organisms)
• Watering plants at their base instead of all over (drip irrigation systems are best)
• Keeping garden weeds at bay
• Proper mulching (preferably compost)
• Following plant-specific guidelines. For example, some plants have a tough time when transplanted while others are more sensitive to soil and air temperature fluctuations. You should also be sure that each type of plant gets the water it needs. See the following pages for plant-specific guidelines:
  • Vegetable planting guide
  • Herb garden plants: growing herbs from seeds
  • List of all fruits
  • How to grow flowers

Also recognize that a munched on-plant is not the end of the world. Even if pests get to your seedlings, as long as your garden’s conditions are ideal you’re crops should still produce a bountiful harvest.

Prevention: Level 2 – The Pest-Reducing Garden Layout for Organic Garden Pest Control (Harmful Insects & Disease)

The concept around deterring harmful insects is simple: don’t offer up your crops on a silver platter. Put yourself in their shoes. In a garden that’s thousands of times larger than you and considering there are some crops you can eat and others you can’t, how would you like your meals laid out?

Answer: All together, in the same location, year after year.

In other words (we’ve enlarged back to gardener size now), it’s best if you remove “traditional monoculture (single plant) row gardening” from your vocabulary (as if that were a common phrase).

Plant a variety of compatible crops (i.e. crops that prefer similar soil temperatures, soil pH, watering and won’t shade each other out) and alternate their locations. That way, if a pest does happen upon their favorite meal, they’ll be less likely to find a second course. And while they’re trying, they’ll be more likely to be intercepted by your garden predator allies (discussed in the next section).

For the same reasons, practice appropriate herb and vegetable crop rotation. You don’t want newly emerging larvae from last year’s insects or a persistent disease to have easy access year after year.

And have you ever heard of companion planting charts? The theory goes like this: some plants improve the growing environment for other plants. The actual benefit of this practice is up for debate, but whether companion plants repel pests, improve soil quality or provide a “living mulch” that shades out weeds, there’s certain to be at least a few positives that result from this strategy.

Here are some of the better known natural harmful insect repellents ordered by insect…

Pest	Plant Repellent for Organic Garden Pest Control
Ant	mint, tansy, pennyroyal
Aphids	mint, garlic, chives, coriander, anise
Bean Leaf Beetle	potatoes, onion, turnip
Codling Moth	common oleander
Colorado Potato Bug	green beans, coriander, nasturtium
Cucumber Beetle	radish, tansy
Flea Beetle	garlic, onion, mint
Imported Cabbage Worm	mint, sage, rosemary, hyssop
Japanese Beetle	garlic, larkspur, tansy, rue, geranium
Leaf Hopper	geranium, petunia
Mexican Bean Beetle	potatoes, onion, garlic, radishes, petunia, marigolds
Mice	onion
Root Knot Nematodes	French marigolds
Slugs	prostrate rosemary, wormwood
Spider Mites	onion, garlic, cloves, chives
Squash Bug	radishes, marigolds, tansy, nasturtium
Stink Bug	radishes
Thrips	marigolds
Tomato Hornworm	marigolds, sage, borage
Whitefly	marigolds, nasturtium
Plant Repellant List for Organic Garden Pest Control Reference: Natural Resources Conservation Service

Keep in mind that some of the above – especially when growing a mint plant – can quickly turn from friend to foe by taking over your garden. You can still include the voracious growers with your other plants, just be sure to grow them in a separate container (pot, box, etc.) placed amongst your garden bed plants.

Prevention: Level 3 – Encouraging Predators of Harmful Insects

Even if you garden alone, there is an army waiting in the wings and anxious to help. The final level of prevention focuses on their recruitment.

But keep in mind that you want a natural rise in the predator population without overdoing it… if you overshoot, the predators won’t have enough food and will move on to other yards. So focus on voluntary enlistment rather than purchasing and dispatching a hoard.

Following are the most common garden predators and how to entice them to come and stay…

• Beneficial Animals
• Beneficial Insects

Beneficial Animals for Organic Garden Pest Control

• Bats – these bad boys can kill over 1,000 harmful insects in one night… and that’s just one bat! To keep them close, install a Bat House.
  
  And don’t be overly scared of rabies or bat bites as both are extremely uncommon... just don’t handle them with your bare hands if any fall to the ground.
• Birds – There are lots of ways to attract these insect-loving beauties: plant bushes and trees and add bird houses and feeders at various heights (Gardens Alive has several good options).
  
  While you’re at it, why not indulge them with a birdbath as well? You can even purchase a heated birdbath to keep them around during the winter!
• Snakes – if you can stomach it, allow most snakes to stay in your garden since they love to dine on insects and rodents. The only ones you need to avoid (that is, the only ones that are poisonous to humans) are copperheads, coral snakes, cottonmouths (also called water moccasins) and rattlesnakes (pictured right).

• Toads – One of the most beneficial garden predators, toads feed on just about anything smaller than them including harmful insects (up to 20,000 per year!), snails and slugs.
  
  To attract them, place a garden toad house in or near your garden along with a shallow dish or birdbath with water.

Beneficial Insects for Organic Garden Pest Control

Ambush bugs Aphid Mummy Assassin bugs Big-eyed bug Blister beetle Braconid wasp cocoon Brown lacewing Damsel bug Dragonflies Fireflies (lightning bugs) Green lacewings are extremely effective "all-purpose" harmful insect feeders. They can be purchased online or attracted naturally as described below. Ground beetles Hoverfly Ichneumon Wasp Lacewings Ladybugs (also called lady beetles) – GrowingAnyhing.com’s good ole mascot is a real champion in both larvae and adult form, munching on several thousands of soft-bodied harmful insects throughout their life. To get them in your garden, purchase ladybugs ready to lay eggs (to get double for your money) or attract them using the tips below.

Minute pirate bug Nematode Praying mantis Predatory mites Predatory stink bug Robber fly Rove beetles Soldier beetle Spiders – don’t go stomping spiders or demolishing webs! Those webs can catch countless harmful insects day and night. The only two you need to be afraid of are the brown recluse and black widow (pictured below), so leave the rest alone. Spined soldier bug Tachinid Fly Tiger beetle Tree cricket Trichogrammatid wasp Yellow jackets

Beneficial Insect List for Organic Garden Pest Control Reference: Illinois Dept of Natural Resources

For photographs and descriptions for each of the insect predators listed above, click here. That page also points out how to distinguish between good (predator) and bad (pest) insect eggs and good and bad stink bugs.

To attract most of the above beneficial insects along with other helpers, consider growing an entire bed of predator-attracting plants near your vegetable garden and include at least a few of the following…

• Any type of flowering or fruit-bearing bush to attract birds
• Catnip
• Dill
• Goldenrod
• Grasses
• Hairy vetch
• Perennial alfalfa
• Thyme
• Yarrow

In addition to attracting harmful insect predators, flowering plants will also attract the ever-important bee for pollination.

Organic Garden Pest Control: Level 1 – Gardener Intervention (Harmful Insects, Disease, Mammals, Birds)

Once you’ve gotten your organic garden pest control ecosystem in place by following the advice above, you should be at least three-quarters of the way towards eliminating your pest problems. For any remaining issues, you’ll need to take more direct action…

Old fashioned hand pickin’ – Make the garden rounds a few times a week looking for harmful insects, eggs and larvae, preferably early in the morning. When you find them, do them in by picking or scraping them into a can of soapy water.

Insect barriers are an effective option for preventing harmful insects from ever accessing your plants in the first place. On the downside, they do make it a bit more difficult for you to get in and out for weeding and maintenance.

Insect traps are good for targeting specific types of harmful insects that are attacking your crops. They are available for apple maggot flies, codling moths, cucumber beetles, japanese beetles, peach tree borers and pests going after your apple trees.

Slug and snail bait - Usually made with iron phosphate, slug and snail bait causes these pests to stop eating and die within a few days.

Spray-on insect barriers made from the naturally occurring kaolin clay are applied directly on fruits or vegetables to form a protective barrier from insects. They may also protect against sun damage.

Install fencing to keep small and large animals out. The type you choose depends on the animals that are going after your crop:

• Chicken wire is a good organic garden pest control option for smaller animals. Deer are confused by back to back fences (one inside the other), so higher chicken wire fences - the higher, the better - could work for them as well. For smaller animals, buy enough to reach at least two and a half feet (76 cm) above the soil and 12 inches (30 cm) below the soil (3.5 feet/1.1 m high total).
  
  For added protection from burrowers, add an additional 12 inches (30 cm) perpendicular to and outward from the underground bottom of the chicken wire. This underground L-shape will stop diggers in their tracks.
  
  To prevent climbers such as raccoons from making it over, increase the fence height to at least 4 feet and stop the supporting posts about a foot below the top. When the ‘coons try to climb up, their weight will bend back the fence making it nearly impossible to get over.

• Electric fencing is the more sure-fire way to keep out smaller mammals either in addition to or independent of chicken wire fencing.
  
  The electric fence posts should have two electrified wires: once about 5 inches (12.5 cm) off of the ground and another at about one foot (30cm). If you're using the electric fence to fend off deer, contact a professional as the set-up can be tricky.
• Traditional fencing made of stone or wood will probably keep deer out. Again, the higher, the better.

Birds - Encouraging birds is one of the best natural ways to control unwanted insects, but they can also be pests themselves when they try to steal your hard-earned harvest. Draping netting over your plants and trees is the most effective way to prevent this:

• Try bulk netting for your trees (14 feet x 45 feet (4.3 m x 13.7 m) or 14 feet x 75 feet (4.3 m x 22.9 m))
• Try Bird Barricade Deluxe netting for your plants (14 x 14 feet (4.3 x 4.3 m) or 7 x 20 feet (2.1 x 6.1 m))

Organic Garden Pest Control: Level 2 – Natural Pesticides, Biological Controls & Other Options (Harmful Insects & Disease)

If you’ve tried everything on this page and still have a problem (or if you’re still working on getting your soil and plant health in order for next year), it’s time to bring out the big guns. Here’s what’s in your natural arsenal…

• Biological controls such as beneficial nematodes consist of naturally occurring fungi and bacteria that kill or crowd out disease-causing organisms.
• Animal repellant spray contains ingredients (i.e. egg, pepper, garlic, etc.) that repel animals by virtue of its taste and odor. This version's primary active ingredient is eggs while this one uses hot peppers.
• Insecticidal soap is a plant-derived spray that dries up and kills harmful insects using selected fatty acid salts.
• Neem oil spray is another effective natural option for killing harmful insects.
• Copper and sulfer are probably the most effective “natural” option for killing disease organisms. Unfortunately, they may also kill your benefical soil organisms, beneficial insects and even your plants, so use them sparingly.

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Copperhead photo is licensed under the Creative Commons Attribution 2.5 Generic license. Coral snake photo is licensed under the Creative Commons Attribution-ShareAlike 2.0 Generic license. Rattlesnake photo, cottonmouth photo and black widow photo are licensed under the Creative Commons Attribution-ShareAlike 3.0 Unported license.